Multiple photostabilization actions of heartwood extract from Acacia confusa

Compared to toxic and carcinogenic synthetic photostabilizers, application of plant phenolics as natural photostabilizers is more environmentally friendly. Previous works demonstrated the heartwood extract (HWE) of Acacia confusa has the potential to be a natural wood photostabilizer. However, its exact photostabilities and wood photoprotection abilities are not fully understood. This study aimed to illustrate the photostabilities of the HWE on wood and to recognize the effective components in HWE. The results obtained from the wood photoprotection test and photostability analyses revealed that HWE and its fractions possessed wood photoprotection abilities to retard lignin photodegradation, especially HWE and its EtOAc fraction, due to the abundant catecholic flavonoids endowing the multiple photostabilities, including UVA absorptivity, singlet oxygen quenching ability and phenoxyl radical scavenging efficacy. In addition, the photostability-guided isolation method was successively established for investigating the multiple photostabilization actions of HWE. Accordingly, this method can be applied as the standard procedure for isolating photostabilizers from plant secondary metabolites.